Various applications such as automobile safety devices, laser radars, 3-D imaging, laser tomography, time imaging spectroscopy, etc., require optical sources which generate high-power (10 W to 1000 W) single optical pulses in the picosecond range.
A high-power single pulse can be produced with a semiconductor laser diode which may have a double heterostructure laser chip. To be commercial, the energy of the optical pulse should be produced by low-cost, compact and reliable electric power sources. Suitable and readily available electric power sources can provide an electric pulse having a duration of a few nanoseconds, a reasonably symmetric shape and an amplitude of order 10 A.
There is a need for higher-power optical pulses generated using the low-cost power sources and there have also been attempts to increase the optical power. However, all the attempts have faced serious drawbacks. For example, if the amplitude of the electric current pulse is increased, the power of the optical pulse also increases but after a certain critical value a second optical pulse trailing the primary optical pulse will appear which is highly undesirable. The proposed increase in the volume or dimensions of the active layer may increase the power of the optical pulse but the increase also results in at least one trailing optical pulse. Theoretically, the electric current pulse may be formed such that it has a very sharp trailing end for reducing the probability of a trailing pulse, but that is beyond reach of or at least nontrivial to achieve with the high-power electronics at the moment.